Toys with gimmicks huh? That immediately brings to mind my beloved first alien figures from the classic Kenner alien series from the 90's. Each one had some form of fun wacky gimmick. My favorite was the scorpion alien, which could explode at the touch of a button. Good stuff!
Here's a modern version gimmick alien of my own design, based off of the "Carrier xenomorph" from the game AVP Extinction. I gave it a glow in the dark dome, which works well the eerie alien design. Also you should play the game, if you haven't already. It's super fun.

In the game this alien towers over it's lesser xeno brethren, so to achieve that look, I used the already massive Neca mantis alien, the feet and head are sculpted from scratch, hands are warrior alien hands with sculpt applied. Those back spines are from Shelob. Thankfully the new back armor sculpt NECA uses for the warrior sculpt is one solid piece of plastic, so I was able to successfully dremel out 8 working joint sockets, so the the spines are fully articulated. Finished it up a with two-toned grey paintjob. And finally the tail is from Mcfarlane's battle-damaged AVP queen alien.

Thanks for stopping by!~